1. Field of the Invention
The present invention relates to a film feeding device for a camera into which is loaded a film cartridge arranged to feed or supply a film wound into the roll form therein outwardly through a supply outlet by rotating a spool shaft in the supply direction, and to rewind the film by rotating the spool shaft in the rewinding direction.
2. Related Background Art
As disclosed in U.S. Pat. No. 4,832,275, for example, there and as shown schematically in FIG. 10, has heretofore been proposed a film cartridge 2 comprising a tubular portion 2a for accommodating a photographic film 1 and having a spool shaft therein around which the film is wound in the roll form, and a film feed-out portion 2b provided integrally with the tubular portion 2a to extend in the tangential direction therefrom for accommodating a leading end of the film in the straight form. According to that cartridge 2, the film 1 is progressively fed out from its leading end through a supply outlet at a distal end of the feed-out portion 2b by driving the spool shaft disposed in the tubular portion 2a at its shaft end (i.e., a spline indicated by 2c in the drawing) to rotate in the supply direction of the film 1 (i.e., in the forward direction as indicated by the solid arrow in the drawing), whereas the film 1 is rewound by driving the spool shaft in the rewinding direction (i.e., in the backward direction as indicated by the broken arrow in the drawing), so that the film leading end may be returned into the feed-out portion 2b. Note that in this example, perforations 1a, 1a are successively formed in the upper and lower edge portions of the film 1, respectively, as with a 135 type film.
With such a cartridge structure, the leading end of the film 1 is held withdrawn into the cartridge 2 when the cartridge is loaded or set in a camera, or when the film is rewound to remove the cartridge out of the camera after the completion of photographing. Furthermore, because the film 1 can be automatically fed out with the spool shaft driven by an electric motor to rotate, a setting operation of the film 1 into the camera becomes so very simple that a user may easily handle the film 1.
However no prior art has yet disclosed practical examples relating to camera structures and their internal mechanisms capable of loading the above type cartridge 2, in particular, relating to which mechanism is to be employed to feed the film 1 out of the cartridge 2, wind it frame by frame, and then rewind it into the cartridge 2. It is therefore desirable to realize a camera equipped with a supply mechanism, a winding mechanism, a rewinding mechanism for a film, etc., which can make full use of advantages of the cartridge structure as explained above.
In realizing such a desired camera, what is especially required is to supply, wind and rewind the film by a film driving mechanism with the necessary minimum number of parts and a simple structure. It is also required to arrange respective mechanism components with high efficiency, and construct the entire structure in small and compact size. Another requirement is to operate the respective mechanism components in a stable and reliable manner. Thus, some steps for meeting all of those requirements must be taken.
One of the problems encountered in such a film feeding device for a camera is the relationship between a supply drive system for feeding the film 1 out of the cartridge 2 and a winding drive system for taking up the film 1. More specifically, the film supply drive system is operatively coupled to the spool shaft of the cartridge 2 for rotating the film 1 in the supply direction, whereas the film winding drive system is operatively coupled to a winding spool driven to attach and wind the film leading end around the spool, so that the film 1 is given a pulling force and taken up frame by frame. These two drive systems are interconnected through the film 1 and the spool shaft of the cartridge 2, and are arranged to provide respective rotations in the same direction. For simplification, it is preferable to operate both the drive systems by using a single drive source for rotation. But, the constructive arrangement necessary to operate the cartridge 2 and the winding spool disposed on opposite sides by using the single drive source is likely to complicate, taking into account the relationship of the above two drive systems and a rewinding drive system as well. For this reason, the two drive systems are desirably driven by respective drive sources separate from each other. This, however, requires intricate control such as properly controlling the timings in respective operations to avoid mutual interference between the two drive systems, and also makes the structure more complicated. It is thus desired to be able to solve those points.
In addition, the problem faced in arranging the drive systems for supplying, winding and rewinding the film 1 raises a requirement to dispose the constituent elements of the respective systems at locations out of interference with a film passage defined in an aperture section through which a beam of light is projected onto the film 1 for photographing. There are sometimes not left sufficient spaces above and below the film passage. These points must also be taken into consideration.